In recent years, the number of community services typified by the SNS (Social Networking Service) has increased. Functions of the community services include one to link users with one another. For example, on a site screen for a given user, user IDs or the like of other users linked with the user are displayed.
Possible methods for linking users with one another include a method of causing each user to perform an operation for linking for oneself. However, the user tends to care about whether the user may give a favorable impression to another counterpart user when the user performs the operation for linking the user with the counterpart user on one's own. This is one reason why, based on actual situations, user will not decide to link or delink with others actively.
It may be therefore desirable that the linking and delinking of users are automatically performed on the part of a community server that provides a community service. As techniques therefore, for example, Patent Literatures 1˜3 disclose techniques for delinking users who have not communicated messages or the like for a certain period on the part of the community server.